The present invention relates generally to the field of illumination and, more particularly, the invention relates to a solid-state lighting source such as a light-emitting diode (LED) device that provides for multi-level illumination in emergency or temporary situations that demand such.
Frequently, homes, offices and industrial plant facilities experience many types of emergency situations involving power failures where an interior or an exterior area has no light. Electrical short circuits, brownouts, fire, accidents, natural disasters (i.e. floods, hurricanes, tornadoes, etc.) or a planned shutdown of electricity may cause these power failures to a facility or dwelling. As a result of these emergencies, most facilities, and especially residential homes, do not have emergency generators to provide temporary back-up lighting or are limited to emergency lighting in the form of portable light sources, such as flashlights or lanterns.
Conventionally, incandescent light bulbs have been used in most of the emergency lighting devices, such as flashlights. However, incandescent bulbs are generally inefficient in terms of energy use and subject to frequent replacement due to their limited lifetime. Light Emitting Diodes (LEDs) have become an attractive alternative as a lighting source in emergency lighting devices. LEDs consume a fraction of the energy used to illuminate incandescent bulbs, therefore costly electrochemical power, typically battery power, is preserved. By comparison, LEDs implemented in a lighting array will require ninety percent less energy to produce optimum lumen output than that required by a similar incandescent lighting element. Additionally LEDs have a much longer use-life than conventional incandescent bulbs. However, in battery operated devices as electrical power is withdrawn from the cell, the voltage available across a given current load will decrease. This decreased available voltage across the given load causes reduced light output, gradually dimming the light as the battery charge depletes. LEDs have voltage, current and power parameters that must be controlled in order to maximize the extended device life. For an example of a flashlight device incorporating the use of LEDs see U.S. Pat. No. 6,095,661, entitled xe2x80x9cMethod and Apparatus for an LED Flashlightxe2x80x9d, issued on Aug. 1, 2000 in the name of inventor Lebens et al.
While LEDs have many exciting and practical characteristics that make them attractive to new applications, they also present technical limitations such as narrow band spectra, extremely directional light distribution, and reliability concerns. Attempts have been made to address the directional limitations in numerous inventive ways. See for example, U.S. Pat. No. 6,227,679, entitled xe2x80x9cLED Light Bulbxe2x80x9d, issued on May 8, 2001 in the names of inventors Zhang et al. The Zhang ""679 patent addresses the directional limitations by providing for an array of LEDs in which the individual LED units are concentrically mounted and point at various angles to attempt to provide equal light intensity throughout the viewable lighting area.
Reflection means have also been implemented to try and compensate for the directional limitations of the LED. See for example, U.S. Pat. No. 6,234,645, entitled xe2x80x9cLED Lighting System for Producing White Lightxe2x80x9d, issued on May 22, 2001, in the name of inventors Borner, et al. In the Borner ""645 patent an array of LEDs are mounted on the periphery of a circle and pointing in the direction of the reflector and the area to be lighted. The light emitted from the LEDs is reflected off of a conical shaped reflector and directed outward. Also see for example, U.S. Pat. No. 6,149,283, entitled xe2x80x9cLED Lamp With Reflector and Multicolor Adjusterxe2x80x9d, issued on Nov. 21, 2000, in the name of inventors Conway et al. The Conway ""283 patent teaches the use of an array of LEDs disposed in a circular array and pointed toward a reflector and away from the area to be lighted. The light emitted from the LEDs is reflected off a circular, dome shaped reflector and directed outward toward the area to be illuminated. While these reflection means have made some improvements in providing LED light with greater directional capacity, further improvements are still desired to provide broader illumination coverage in emergency lighting devices that implement LEDs.
A need exists to develop an electrochemical LED lighting system capable of providing prolonged illumination over the life of one battery pack. By providing for long-term, interim illumination a solution to electrical service disruption will be gained, especially in areas such as stairwells, bathrooms, corridors, kitchens and offices.
An additional need exists to develop an LED lighting device that is capable of providing wide area illumination coverage. By providing for a device with wide area illumination coverage the device will have useful application in a variety of tasks that include building trades, maritime operations, recreational camping and the like. Additionally, the device should provide for a highly portable unit that can affixed to walls or ceilings, or a free-standing unit that can be positioned on a table, counter or the like.
Also, a need exists to develop a multi-level lighting scheme that will provide identification of the lighting device and the immediate surrounding area so that the device can be located when electrical service interruption occurs. The multi-level lighting scheme should also provide different levels of lighting (i.e., mid-level illumination and maximum illumination) to accommodate the degree of lighting necessary to sufficiently illuminate the area.
The present invention provides for an improved emergency or interim lighting device and associated methods for providing emergency or temporal lighting. The device of the present invention satisfies the need for an electrochemical lighting system capable of providing prolonged illumination over the life of the electrochemical power unit. The device benefits from the use of light emitting diodes (LEDs) as the illumination source, which provide optimum lumen output with considerably less power consumption than conventional incandescent lighting devices. By providing for a unique combination of diode arrangement and reflector the present invention overcomes the directional limitations of conventional LED lighting devices and results in wide area illumination coverage. Additionally the multi-level lighting scheme of the present invention provides for a means of identifying the device during electrical power outage and providing multiple levels of lighting intensity.
In one embodiment of the invention a lighting device that is capable of providing long-term, interim lighting includes an array of Light Emitting Diodes (LEDs) in electrical communication with corresponding electrical circuitry. The array will typically be configured in an elliptical pattern although other patterns such as generally conical, generally circular and the like are also feasible and within the inventive concepts herein disclosed. In one specific embodiment the LEDs comprise both amber and white LED units. The device also includes a means for providing electrical energy to the array of LEDs. In many embodiments the chosen source for electrical energy will be a direct current source, such as an electrochemical source. However, it is also possible to provide energy to the LEDs via other forms such as solar power, conventional alternating current power or any other means of supplying electrical energy.
The lighting device also includes a parabolic reflector positioned proximate to the array of light emitting diodes that reflects light from the LEDs to provide a wide area coverage of illumination. The geometric relationship between the LEDs and the parabolic reflector aids in dispersing the lumen output such that the lighting device is capable of broadcasting a wide-area blanket of light from the reflector. In one embodiment of the invention the elements comprising the LED array face inward toward the parabolic reflector with the reflected light be transmitted outward toward the area to be illuminated.
In another embodiment of the invention a lighting device that is capable of providing multi-level illumination includes an array of LEDs in electrical communication with a circuit board, the array comprising one or more low luminance LEDs and one or more high luminance LEDs. The array will typically be configured in an elliptical pattern although other patterns such as generally conical, generally circular and the like are also feasible. In one specific embodiment the low luminance LEDs comprise amber LED units and the high luminance LEDs comprise white LED units. The device also includes a means for providing electrical energy to the array of LEDs. In many embodiments the chosen source for electrical energy will be a direct current source, such as an electrochemical source.
This embodiment will also include electrical circuitry disposed on the circuit board that provides for engaging the one or more low luminance LEDs in a first level of illumination, engaging the one or more high luminance LEDs in a second level of illumination and engaging the one or more low luminance LEDs and the one or more high luminance LEDs in a third level of illumination. Additionally the electrical circuitry may include a means for accelerating the flow of electricity to the high luminance LEDs to increase the intensity of light output by the lighting device.
In another embodiment of the present invention a multi-level security illumination device includes a switch for engaging multiple levels of illumination and a processor in electrical communication with the switch that determines the level of illumination based on signals from the switch. The device additionally includes a first bank of light emitting diodes in electrical communication with the processor that provides low intensity illumination based on signals from the processor and a second bank of light emitting diodes in electrical communication with the processor that provides high intensity illumination based on signals from the processor. Additional processing means are provided for that increase current to the second bank of light emitting diodes to affect a maximum amplification level of illumination.
The invention is also defined by a method for multi-level illumination. The method comprises the step of engaging one or more low luminance Light Emitting Diode (LEDs) that are disposed in a LED array to provide first level illumination for the purpose of illuminating the location of the light source, followed by the step of disengaging the one or more low luminance LEDs and engaging one or more high luminance LEDs that are disposed in the LED array to provide second level illumination for the purpose of illuminating a specified area proximate the light source. The method follows with the step of engaging the one or more low luminance LEDs, in conjunction with the previously engaged one or more high luminance LEDs to provide third level illumination for the purpose of further illuminating the specified area proximate the light source. Additionally the method may comprise the step of accelerating the flow of electricity to the one or more high luminance LEDs for the purpose of increasing the intensity of illumination to a maximum amplification.
As such the present invention provides for an LED lighting system capable of providing a prolonged interim illumination solution in instances where electrical service disruption occurs. In the electrochemical energy embodiments this results in long-term use over the lifetime of a single battery pack. In providing for such devices, the present invention is especially attractive as a temporary lighting alternative in stairwells, bathrooms, corridors, kitchens and offices.
Additionally, the unique geometric combination of the LED array and the parabolic reflector provide for wide area illumination coverage. Such devices will have much needed applicability in a variety of tasks that include building trades, maritime operations, recreational camping and the like.
The multi-level lighting method of the present invention will provide ongoing identification of the lighting device allowing for easy identification of the device in instances in which electrical service disruption occurs. In addition, by providing for different levels of lighting (i.e., mid-level illumination and maximum illumination) to accommodate the degree of lighting necessary the device is capable of preserving battery life and, thus, prolonging the lighting period.